While some of the crossovers may be recognizable, like Natalia Tena as Tonks and Osha, others may come as a surprise.

Here are 13 actors who have appeared in both series:

1/

Michelle Fairley made a brief appearance in the first part of "Harry Potter and the Deathly Hallows" as Hermione's mother.

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But "GOT" fans might know her best as the strong-willed Catelyn Stark.

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Natalia Tena is known throughout the "Harry Potter" fandom as the amazing Nymphadora Tonks, but don't call her Nymphadora.

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She joined "GOT" as the fearless wildling Osha in the first season until she and Rickon disappeared for a bit during seasons four and five. She briefly returned in season six, but she was killed by Ramsay Bolton when she tried to stab him. RIP Osha.

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David Bradley played Argus Filch, the often cruel caretaker of Hogwarts.

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He plays Walder Frey, the awful head of House Frey who betrayed the Stark family, in "GOT."

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Ciarán Hinds played Aberforth Dumbledore, Albus' brother, in the final "Harry Potter" movie.

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Fans might recognize him as Mance Rayder, the King Beyond the Wall, in "GOT."

He showed up during the sixth season of "GOT" as Dickon Tarly, Sam's younger brother.

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You won't recognize Julian Glover in Harry Potter, because he was the voice of Aragog, the giant spider.

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But you can recognize him as Grand Maester Pycelle in "GOT."

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Standing at 7-foot-1, Ian Whyte has played his fair share of giant characters, including the whole body shots for Madame Olympe Maxime, also portrayed by Frances de la Tour.

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He's portrayed multiple characters on "GOT," including a White Walker, the Mountain in season two, and Wun Wun the giant.

Courtesy of HBO

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Nicholas Blane made an appearance in "Harry Potter and the Order of the Phoenix" as Bob, a wizard who worked with Arthur Weasley at the Ministry of Magic. Bob is the one holding the box.

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In "GOT," he played the Spice King, one of The Thirteen who rule Qarth. He was killed by fellow member and warlock Pyat Pree.

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Bronson Webb played a Slytherin student and friend to Draco Malfoy in "Harry Potter and the Prisoner of Azkaban." He's the one on the right.

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Webb played Will, a member of the Night's Watch who fled from the White Walkers only to be executed by Ned Stark for deserting his men.

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Ralph Ineson plays Amycus Carrow, a Death Eater in three "Harry Potter" films. He's on the right.

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In "GOT," he played Dagmer Cleftjaw, a raider for House Greyjoy. But after betraying Theon at Winterfell and stabbing Maester Luwin, Dagmer was in for a rude awakening when he and his men were flayed alive by the sadistic Ramsay Snow.

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Edward Tudor-Pole played Mr. Borgin, an owner of Borgin and Burkes, in a deleted scene from "The Chamber of Secrets."

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He popped up as a protester in a season-two episode of "GOT."

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Sally Mortemore played Irma Pince, the librarian at Hogwarts, in "Harry Potter and the Chamber of Secrets."

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She popped up on "GOT" as a Braavosi woman in the sixth season.

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Blink and you'll miss Daniel Tuite as the "skinny ministry wizard" in "Deathly Hallows: Part 1." He's somewhere in there.

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But he has a more prominent role in "GOT" as Lothar Frey in the newest season.